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Fish FISH DIVISION
Regulating harvest, protection, and enhancement of fish populations
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Coho Salmon

Life History

Coho SalmonThe coho salmon life history is relatively straight-forward. Smolts typically migrate to sea in the spring of their second year, spend 16-20 months rearing in the ocean, then return to freshwater as three-year-old adults. A returning adult may measure more than two feet in length and weigh an average of eight pounds. After the first summer at sea, a small proportion of the males reach early sexual maturity and return that fall as two-year-old “jacks.” These jack returns have proven to be a fairly accurate predictor of adult abundance the following year, and serve as a key component for setting ocean coho fishing regulations.

Oregon is on the southern range of coho production that extends from Point Hope, Alaska to Monterey Bay, California. Scientists have identified wild coho populations in Oregon coastal rivers ranging from the Necanicum River, at Seaside, on the north to the Winchuck River near the California border. Together, these populations comprise a group of fish known as Oregon Coastal Natural coho, or OCNs. Most of these fish originate in waters from the Coquille River north to the Nehalem River. Three centralcoast lake basins (Siltcoos, Tahkenitch and Tenmile) are also important coho producers.

While coho also live in some south-coast rivers, such as the Rogue, their numbers have been historically small compared to waters farther north.

Habitat Requirements

Nature tends to fill niches. While the larger chinook salmon requires big water, often low in a watershed, for spawning, coho are drawn to the next level of tributaries. A checklist of typical coho fresh water habitat follows.

  • Small, relatively low-gradient tributary streams for spawning and juvenile rearing
  • May use lakes for rearing where available
  • Pea to orange-size spawning gravel
  • Over-winter primarily in off-channel alcoves and beaver ponds, where available.
  • Prefer complex instream structure (primarily large and small woody debris) and shaded streams with tree-lined banks for rearing.

Natural Production

Wild coho spawner abundance declined in the early 1970s, and has fluctuated at these levels ever since. Maximum sustained yield annual spawning escapement goals have not been reached since 1986, despite sometimes heavy harvest restrictions. However, spawning levels have been greater than 70 percent of this goal in six of the past 10 years.

Scientists note a variety of potential causes affecting coho production including rearing and spawning habitat loss, low summer water flows, blocked upstream passage, harvest, hatchery releases and a changing ocean environment.

Many freshwater environmental impacts affecting coho are human-related. The concern about a poor ocean coho survival, however, reflects an apparent shift in the eastern Pacific Ocean. Scientists have documented changes in ocean currents and temperatures off the California, Oregon and Washington coasts that have persisted, with a few exceptions, since the late 1970s. These changes, which create a more hostile environment for coho in this area, appear to be a major cause for poor coho production in Oregon in the last decade. In spite of these conditions, numbers of returning spawners have remained stable.

Hatchery Production

The Oregon Department of Fish and Wildlife operates eight public hatcheries along the Oregon coast, producing about five million coho salmon smolts annually. Seven Columbia Basin facilities operated by the state of Oregon, such as Bonneville, Big Creek and Sandy hatcheries release almost 10 million young coho annually.

Since the 1970s, adult catch from all hatchery releases has averaged more than one million fish annually and comprised about 70 percent of the total ocean sport and commercial harvests. In 1994 and 1995, however, even hatchery adult production is expected to be well below the average returns over the last 20 years — reflecting what scientists describe as the poorest ocean habitat conditions in 100 years.

Harvest

OCNs are one of the largest remaining aggregates of wild coho populations in the United States outside of Alaska. Even so, achieving desired spawning goals has been a problem in the last decade. Efforts to protect these wild populations have been the “driver” affecting ocean fishing seasons the last three years, and bay and river sport fisheries since 1993.

Coho fishing restriction reached the ultimate extreme this past summer when the PFMC and member states shut down all targeted coho fisheries from the Canadian border to Mexico and the Oregon Fish and Wildlife Commission severely limited coastal bay and river catches.

These populations contribute most heavily to fisheries in the Oregon Production Index (OPI) area, which includes ocean waters from Leadbetter Point, Washington south into California. Still, harvest of both OCN and Oregon coastal hatchery coho together comprise just onethird of total coho harvest in the OPI area. The remaining coho come primarily from the Columbia River system and, to a lesser extent, from coastal Washington production.

Virtually all Oregon production of Columbia River coho originates from mainstem and tributary hatcheries. Natural coho populations still exist on the Clackamas and Sandy rivers.

Coho Status Review Process

Coho salmon have been under close scientific inspection and strict harvest management for years. Department staff have been conducting studies and gathering the best available data from a variety of sources. A presentation to the Fish and Wildlife Commission in February of 1995 on whether to list Oregon's coastal and lower Columbia River coho salmon under the state Endangered Species Act reflected investigations in three specific areas:

  • Identification of “district population segments” as required under the state Endangered Species law: What and where are these populations, and why do they potentially qualify for listing consideration?
  • Trends and abundance in coho production: What do the numbers show about the past, current and future performance of fish within identified population segments?
  • Risk Assessment: Are future factors affecting these populations likely to get better...worse...or remain about the same?

Applying Oregon Endangered Species Act Criteria

The Commission decided not to list the coho in February 1995. This decision was based on circumstances and information presented which did not justify a listing as threatened or endangered based on legal requirements. The Oregon Endangered Species Act sets out specific criteria and procedural requirements which must be met if the Fish and Wildlife Commission is to list a species as threatened or endangered.

In order to determine whether a native species is threatened or endangered with extinction, the commission is required to determine, based on the best available scientific and other information, that the natural reproductive potential of the species is in danger of failure due to limited population numbers, disease, predation, or other natural or man-made factors affecting its continued existence.

In addition, the Commission is required to determine that one or more of the following factors exists:

  • that most populations are undergoing imminent or active deterioration of their range or primary habitat;
  • that overutilization for commercial, recreational, scientific, or educational purposes is occurring or is likely to occur, or
  • that existing state or federal programs or regulations are inadequate to protect the species or its habitat.

Oregon ESA Law Has Limits

The most direct effect of listing a species as threatened or endangered under the Oregon Endangered Species Act is on state-owned or leased lands. Private lands are not directly affected by the Oregon ESA. The state law is advisory- only for federal land managers

State agencies work together to implement conservation programs adopted by the Commission, and Department of Fish and Wildlife biologists act as scientific consultants to other land and water managers to advise whether a management action can affect survival or recovery of a listed species.

Related Federal Petitions

The state coho ESA petition review process and decision making efforts are not directly connected to the federal review process. The National Marine Fisheries Service, a branch of the U.S. Department of Commerce, has a separate review process under the federal Endangered Species Act. Oregon Department of Fish and Wildlife biologists have been actively involved as consultants to the federal process. The state, however, is under no legal obligation to adopt any federal findings.

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